// compile: make data
// run: ./data < data.in
#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#ifdef LOCAL
#include <debug/codeforces.h>
#define debug(x...) _debug_print(#x, x);
#define Debug(x...) _debug_print_format(#x, x);
#else
#define debug(x...)
#define Debug(x...)
#endif
template<typename...Args> void print_(Args...args){((cout<<args<<" "),...)<<endl;}
#define VI vector<int>
#define VII vector<vector<int>>
#define VIII vector<vector<vector<int>>>
#define rep(i,a,b) for(int i=(a);i<(int)(b);++i)
#define sz(v) ((int)(v).size())
#define print(...) print_(__VA_ARGS__);
#define FIND(a, x) ((find(a.begin(),a.end(),(x))!=a.end())?1:0)
#define cmin(x,...) x=min({(x), __VA_ARGS__})
#define cmax(x,...) x=max({(x), __VA_ARGS__})
#define INTMAX (int)(9223372036854775807)
#define INF (int)(1152921504606846976)
#define NaN (int)(0x8b88e1d0595d51d1)
#define double long double
#define int long long
#define MAXN 200010

struct Tree {
    int n;
    vector<vector<int>> e;
    struct node {
        vector<node*> ch;
        node* parent = nullptr;
        int size;
    };
    vector<node> vertex;
    node *root;
    Tree(int V) {
        n = V;
        e.resize(n);
        vertex.resize(n);
    }
    void add_edge(int u, int v) {
        e[u].push_back(v), e[v].push_back(u);
    }
    int ind(node *x) {return x - &vertex[0]; }
    void build(int rt = 0) {
        function<void(int, int)> dfs = [&](int u, int pre) {
            vertex[u].size = 1;
            for (int v: e[u]) {
                if (v == pre) continue;
                vertex[u].ch.push_back(&vertex[v]);
                vertex[v].parent = &vertex[u];
                dfs(v, u);
                vertex[u].size += vertex[v].size;
            }
        };
        root = &vertex[rt];
        dfs(rt, -1);
    }
    pair<int, pair<int, int>> diameter() {
        int maxd = -INF, s = -1, t = -1;
        vector<int> vis(n, 0);
        function<void(int, int, int&)> dfs = [&](int u, int dis, int &st) -> void {
            vis[u] = 1;
            if (dis > maxd) maxd = dis, st = u;
            for (auto v: e[u]) if (!vis[v]) dfs(v, dis+1, st);
        };
        dfs(ind(root), 0, s);
        maxd = -INF, fill(vis.begin(), vis.end(), 0);
        dfs(s, 0, t);
        return {maxd, {s, t}};
    }
    void graphviz_dump(int plus = 0, string filename = "graph.dot") {
        FILE *f = fopen(filename.c_str(), "w");
        fprintf(f, "digraph Tree {\n");
        rep(i, 0, n) {
            node *x = &vertex[i];
            fprintf(f, "    %lld;\n");
        }
        rep(i, 0, n) {
            node *x = &vertex[i];
            for (auto y: x->ch) {
                fprintf(f, "    %ld -> %ld;\n", x - &vertex[0], y - &vertex[0]);
            }
        }
        fprintf(f, "}\n");
    }
};

int32_t main() {
    ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);

    int n; cin >> n;
    Tree g(n);
    rep(i, 0, n-1) {
        int u, v; cin >> u >> v;
        g.add_edge(u-1, v-1);
    }
    g.build(0);
    auto res = g.diameter();
    cout << res.first << endl;

    return 0;
}